Means and method for cathode ray oscilloscope observation and recordation



March 14, 1944. F w FRINK .MEANS AND METHOD 1 0R CATHODE RAYOSCILLOSCOPE OBSERVATION AND RECORDATION 2 Sheets-Sheet 1 Original FiledJan. 25, 1958 Q I s, 3.

1 INVENTOR SI M BY ZZ'WMMATTORNEY March 14, 1944. F. w. FRINK 2,344,296

MEANS AND METHOD FOR CATHODE RAY OSCILLOSCOPE OBSERVATION ANDRECORDATION Original Filed Jan. 25, 1938 Sheets-Sheet 2 INVENTOR MATTORNEY eiaei Mar. id, 1944 I 52,344,296,

MEANS AND METHOD FGR CATEGDE BAY QSGHJLOSCOPE UBSERVA'EIQN ANDEECORDATIGN Frederick W. Frinlx, New York, N. Y.

@rlglnnl application January 25, 1938, Serial No.

issues. mvlded and this application November 29, 1940, serial No.867,707

8 @iaims. (Cl. 2171-95) This invention relates to improvements incomment of low priced cathode ray oscilloscope tubes, paring theoutlines of forms traced onthe screens an oscilloscope can now beequipped O c t d y Oscilloscopes. tubes at moderate cost. Such anoscilloscope The main je e invention 18 o p omay have a commonhorizontal sweep circuit and vide improved means which shall increasethe 5 when so equipped can be used for simultanecfi cie and accuracy ofresults produced y ously viewing the images of two voltages especiallydevices 0! t e cha cter defi i h those whose frequencies are equal orharmoni A fu t er ject of t e invention s to provide cally related. Suchoscilloscope is not open to ior simultaneously viewin r h t a hin theabove mentioned objections applying to also and fi d comparing. thecathode i? tronic switching circuits. However, in order to imagesproduced by two or more voltages. By the compare the two cathode my tn tcomparison as prov d for by this invention the curately it is desirableto be able to superpose differences In two outlines. as for instance thethe two outlines, one on the other, and this can WW8 forms W0 Periodic701158563, may be be done according to the present invention by paredand this be availed to (impale giving the outlines of the separatecathode ray W given outline, &S for instance a voltagewave tubes theappearance of being superposed. one form, with a standard outline, forinstance a on t other.

standard Nudge Wave form whereby the A further object of the inventionis to provide cidence with or divergence from the standard an improvedmethod which shall increase the Waive may be mted- To make msslble thecuracy of, and the eiiiciency oi producing, results comparison oi, forinstance, the wave forms of as indicated. two periodic voltages, deviceslmownas electronic A fu th object of the invention is to pro switchingcircuits have been used. These circuits de for 11 Mm a 6 function insuch a manner that the vertical degi y tr g nd I cording cathode myflection plates of the cathode ray tube are con-- nected to the twosources oi voltage alternately, ig ig g ggfig gi gg i zgggg g thecommutation occurring at a frequency high outlines enough so that thecurves produced by the two voltages appear to be present on the screencon 80 flg i z i gg gig ggifeii fiefi cla iin $1??? tinuously andsimultaneously. Such circuits are pear hereinaften useful in variousapplications, such for example,

as comparing the audio frequency output voltage This appncatmn isdivlsmn of my D oi a modulator tube with the modulation envelopepucation serial Number filed a a y of the high frequency wave which itmodulates. 25, 1938- Such circuits are, however, complicated and exas nthe ompany n drawi whi h mus pensive and are open to the objection thatthe trate the inventionvoltages to be studied must be passed throughFig. l is a side elevation, partly in section, of amplifier tubes, whichare used as switches for, apparatus embodying the invention:

connecting and disconnecting the two sources of Fig. 2 is a sideelevation of the apparatus oi voltages. These amplifier tubes may changethe 40 Fig. 1 viewed on the line 2-2 of Fig. l: pp r n f h resultingcurves. y in r Fig. 3 is a section, on an enlarged scale, on the ingfrequency, phase, or amplitude distortion, line H of mg 1 showing thecathode ray g high 222: 32 $3 3 5: 3 3: fiection plates and also theconnection of the cirare engsue. Furt gradual deterioration of theamplifier tubes, deg g g g of apparatus for slmuh iiective results maybe obtained, before it is taneo'usiy viewing and comparing images onrealized that the tube characteristics have bethr r more cathode mtubes? come inadequate. Another disadvantage of the f 68 1 y electronicswitching circuits is the fact that they is an end 8 eva'tlon ofapparatus are not suited f the viewing photographing 5o bodying theinvention wherein a rotating mirror f curves produced by simultaneoustransient is employed in connection with the comparing voltages.Furthermore such circuits are of such 0f the two 056111056098 images; anature that interference might be generated 8- 6 is a ce Vie O e ot ror0t by them when the characteristics of radio equipis- 5;

want are being studied. Because of the develop- Fig. '7 is a sideelevationof apparatus embodying the invention wherein a stereoscopicdevice is used for comparing the images;

Fig. 8 is a top plan view of the apparatus of Fig. '1;

Fig. 9 is a side elevation of the apparatus of Figs. 7 and 8 viewed asindicated by the arrow 4 of Fig. '7; and

Fig. 10 is a diagrammatic view showing the course of the light rays witha different optical arrangement from that shown in Figs. 7, 8 and 9.

Referring to the drawings, and first to Figs. 1 to 3 inclusive, thedevice comprises a box I forming a complete enclosure except for windows2 and 3 at which are presented the ends of cathode ray tubes 4 and 5.which ends are provided in a well known manner with a fluorescentscreen. The cathode ray or oscilloscope tubes may each be of thewell-known construction comprising a glass envelope 6, within which is avacuum having at one end a fluorescent screen I, there being at theother end well-known cathode ray generating means, not illustrated, thebeam of cathode rays passing between the pairs of deflection plates 8and 9, the pairs being at an angle of 90 with each other, and thecathode ray beam passir g between these deflection plates impinges uponthe screen causing a luminous spot. The cathode ray tubes are suitablysupported within the box I which may also house other of the apparatus.

Mounted upon the box 5 and bearing against the bracket it is. anotherbox having the top H, ends l2 and i3 and sides i i and 55, but without abottom. Within the box just referred to is supported a reflector I6receiving light rays from the screen 7 along the line ll which reflectsalong the line it to the reflecting surface of the mirror 59, and thencealong the line 2!] of vision through the window 2! in the top i i to theeye 22 or" the observer.

7 The mirror l9, however, is not opaque, but is of the type known as"transparent," semi-transparent" or half-silvered," the medium is beingthus light-transmitting. A mirror such as l9 may be made by depositingaluminum, chroluminum or other suitable metal as is well known on thesurface of the glass by evaporation. Such mirrors are well-known andtherefore their construction and manufacture will not be furtherdescribed here, the essential characteristics being that it shallreflect the rays of light from screen 77 as described, and shall alsotransmit light rays from the screen of the cathode ray tube 5, along theline of vision 28 through the medium !9 to the eye of the observer.

The pair of deflection plates 9 of the tube 5 are disposed fordeflecting the rays horizontally, and this is also true of the plates 9'of the tube 6, while angularly displaced in their respective tubes by 90about the axes of the tubes, from the plates. 9 and 9' are the pairs ofvertical deflection plates 8 and 8. The vertical deflection plates 8 and8' are respectively connected with the conductors 23 and 26 upon whichare respectively impressed the potent als or voltages to be compared.The horizontal eflection plates 9 and 5' are connected in parallel withthe sweep circuit conductors 25, such "sweep circuits being well-knownin the 'art.

The arrangement of a cathode ray tube with horizontal deflecting platesenergized by a "sweep circuit and vertical plates energized according tothe voltage to be examined, is a well-known construction, such a tubebeing known as a cathode ray oscilloscope. It is believed to be new withthis applicant, however,

to provide the same "sweep frequency upon the tubes whereby the graphsor curves of voltages on the tubes may be compared by bringing them intovisual superposition or juxtaposition. This sameness of frequency forboth of the tubes may be brought about as shown in Fig. 3 of thedrawings by connecting the horizontal or sweep circuit deflection plates9 and 9' of the cathode ray tubes, in parallel in the "sweep circuit.

In order that the graph or curve of the tube may be caused to occupy anydesired portion of the fluorescent screen, means is provided in both thecircuit of the voltage to be investigated and of the "sweep circuit ofthe tube for giving a positive or negative bias. This is true of both ofthe oscilloscope tubes. By suitably operating this controlling means thegraph or curve of the voltage may be placed as desired upon the screenof the oscilloscope tube and so the images appearing to the observer maybe given any desired positions with relation to each other. Thus thisbiasing controlling means is produced in the circuit of the deflectionplates 8 by means of a battery 26 to an intermediate point of which isconnected one of the conductors 23 so that when the pivoted switch arm2'! is at its midpoint no part of the battery will be in circuit, but bythrowing this switch arm in one direction or the other to engage withdifferent points of the potentiometer resistance 28, a plus or minusbias (and to any desired amount) as may be desired may be given to thedeflection plates 8. Similarly a battery 29 is controlled to give adesired positive or negative bias to the plates 8', a-battery 3D issimilarly controlled to give a desired bias to the plates 9 and abattery 3! is similarly controlled to give the desired bias to theplates 9'.

As an example of the use of the apparatus just descrtbed, it will now beapparent that if it be desired to ascertain the divergence of a certainvoltage from a true sine curve, the voltage to be investigated may beconnected with one of the circuits 23 or 24 and the other one of thosecircuits is connected with a source of electro-motive-force of true sineform, the two electro-motive forces being of the same frequency. Thesweep circuit 25 also being of the same frequency as the electro-motiveforces across the conductors 23 and 24, and the graphs being disposed onthe tube screens by properly adjusting the bias in the various circuitsas described, the two graphs or curves may be so adjusted as to appearto coincide except where there is a variation from the voltage to beinvestigated from that of the true sine curve. The variation of theinvestigated voltage from the true sine form will thereupon be clearlyapparent. It will be seen that by proper adjustment of the bias in thevarious circuits of the deflection plates of the tubes the graphs orcurves may be made to appear in any desired relation to each other, andit will further be apparent that comparisons of other graphs, curves orimages produced on the screens of the cathode ray tubes may :be comparedin any desired apparent relationship. Preferably the cathode ray tubesare substantially alike so that the application to them of similarvoltages will produce substantially similar graphs or curves on thescreens.

The tubes 5 and 6 are preferably located so that the distance traveledby any ray of light from the screen of one tube to the eye is equal tothe distance traveled from a corresponding point on the screen of theother tube to the eye. This causes the horizontal deflections producedby the "sweep voltage to appear the same on both screens, and alsoprevents the two images from undergoing an apparent motion relative toeach other when the observer's eye is moved slightly from side to side.

A camera might be substituted for the eye of the observer and the imagesphotographed.

It will now be evident that the device as referred to makes possible notonly the viewing and photographing of the images produced :by twoperiodic voltages, but also the .viewing and photographing ofsimultaneous transients, provided a suitable "sweep circuit is used, theimages used or photographed being truly si-multaneouaand uninterrupted.

As is well known the screen of a cathode ray tube may be such that theluminosity at any point persists for a very short, if any, period afterthe removal of the cathode ray beam from that point, or the screen maybe such that the luminosity will persist for a considerable time afterthe removal of the rays. In comparing the voltage images produced by thehorizontal sweep" deflections and the "vertical" deflections asdescribed, it is preferable to use a screen of sufflcient persistence sothat a large part or all of the voltage wave may be observed and anaccurate comparison thereby attained.

wherein the movement of the film provides the sweep" as is well known inconnection with oscillograph recording, such moving film may besubstituted in place of the eye of the observer and the "sweep plates ofthe cathode ray tubes may be omitted. Under such circumstances the shortpersistence type of fluorescent screen should be used.

According to the structure of Fig. 4 a device similar to Fig. 1 can beused for simultaneously viewing and comparing the images on the screensof three or more cathode ray tubes. Thus in Fig; 4 the box I is providedwith the cathode ray tubes 3 5, 35 and 35 having the screens 31, 38 and89 with the mirror at of the totally reflecting type, the mirror ti ofthe transparent type, preferably made so that the amount of lightrefiected is equal to that transmitted, and the mirror 62 of thetransparent type, preferably so made that the amount of light reflectedis twice as great as the amount transmitted. The mannet of makingmirrors of the light transmittin and reflecting properties as describedis well understood in the art.

With this arrangement the light rays from the screens 31, 88 and 89 willbe propagated into the line of vision 63 of the eye 44 of the observer,the paths of propagation being indicated by the dot and dash lines.

It will be observed that the screens are so placed that the lengths ofthe paths of the light rays from the respective screens to the eye ofthe observer are of substantially the same length, i. e., the paths ofsuch light rays to the reflecting surface directing the rays to the eyeof the observer are equal.

device, similar to that of Fig. 1. may be used in place of the opticalmeans of Fig. 4, to compare the image on the screen of the middle tubewith theimage on the screen of either of the other tubes. In fact thetwo mirror device would give clearer vision of the images because theamount of light received from each image would be greater.

Referring to the apparatus of Figs. 5 and 6, the box I has mounted in itthe cathode ray tubes and 46 having the screens 41 and 48. Also there issupplied, supported upon the box I", an optical device comprising thebox 39- and the totally reflecting mirror 50 reflecting the light raysfrom the screen of the tube 45 to the line of vision 5! of the eye ofthe observer 52. A rotating mirror 53 of a shape as indicated in Fig. '6is fixed upon the shaft 54 of an electric motor 55 suitably supportedupon the box I". As the blades of the mirror 53 pass across the line ofvision 5|, the light rays from the mirror 50 are reflected to the eye ofthe observer, but when the blades of the mirror are not in this line ofvision the light rays from the screen A8 pass between the blades to theeye of the observer. As the mirror is rotated the light rays from theimage on the screen 6'! and those from the image on the screen 38 willbe alternately seen, and if the speed of rotation'of the mirror is greatenough there is no serious flicker but the images on the two screensseem to be viewed simultaneously.

If a piece of white cardboard is laid on the surface 56 of the box I", atracing can be made of the image produced by the cathoderay tube 45 asthis image appears to be projected upon the cardboard. By moving themotor backwardly, its brackets being secured in the holes 57, and movingthe box 49 with its optical devices as referred to, back a correspondingdistance, namely to the surface 56, it is possible to make a tracing ona cardboard placed on the surface I58, of the image appearing on thescreen 68, so that the images on the screens iii and 48 can be compared.

In Figs. 7, 8, 9 and 10 is shown a stereoscopic device which may be usedfor comparing the images produced on cathode ray oscilloscope screenswhich may have circuit connections for producing the images to becompared as described in connection with the apparatus of Fig. 1. Thusin Figs. 7 to 10 inclusive, the cathode ray tubes 58 and 59, having thescreens 60 and Bi respectively are mounted in a supporting box 62 whichmay house other apparatus as desired.

Supported in a bracket 63 secured to the box are lenses 6% and 65,corresponding respectively to the eyes 66 and B7 of the observer, theeyes respectively observing the fluorescent screens 68 and Si throughthese lenses. If the light rays from the images on the screens 60 andiii fall upon corresponding portions of the retinas of the eyes 66 and67 they appear to be superposed and can therefore be accuratelycompared. To accomplish this the eye 66 must be oriented for viewing thescreen 60 while the eye 67 is oriented for viewing the screen 6!. Thiswould be a difficult condition to attain without lenses, because thefocusing function of the eyes is psychologically connected to theorienting function in such a manner that the eyes .tend to orientthemselves for a distance equal to that for which they are focused andthis would cause each of the eyes to be oriented for viewing 60 alone orH alone. The use of biconvex or piano-convex lenses not only magnifiesthe cathode ray images but also places the optical images so far fromthe eyes that the eyes have little or no difllculty in attaining thenecessary parallel orientation. In connection with the apparatus ofFigs. 7 to 9 it was assumed that the center to center distance betweenthecathode ray sections was approximately equal to the interpupillarydistance between the eyes. If the center to center distance between thescreens were much greater than the interpupillary distance, as would bethe case if large cathode ray tubes were used, prisms 68 may be placedin front of the lenses as shown in Fig. 10 to cause the light fromcorresponding portions of the two screens to strike correspondingportions of the retinas of the eyes. As an alternative the prisms mightbe combined with the lenses as they are in the known device known as thelenticular stereoscope. V

While the invention has been illustrated in what are considered its bestapplications it may have other embodiments without departing from itsspirit and is not therefore limited to the structures shown in thedrawings.

What I claim is:

1. The combination with aplurality of cathode ray tubes having screensadapted to become luminous under the influence of the cathode rays, eachof said tubes having pairs of deflection plates tor deflecting thecathode rays, said pairs of plates being displaced from each otherangularly about the axis of the tube, of means for impressing voltagesfrom different sources upon pairs of said deflection plates in differenttubes, means for impressing 'sweep" voltages of the same frequency uponthe other pairs of deflection plates in said tubes respectively, andlight-deflecting means for causing the lines of the luminous traces uponsaid screens to appear to the vision of the observer to I be superposed,said deflecting means being nondiffusing whereby each of said luminouslines as traced upon said screen shall be preserved in its originaldefinition to the vision of the observer.

2. The combination with a plurality of cathode ray tubes having screensadapted to become luminous under the influence of the cathode rays, eachof said tubes having pairs of deflection plates for deflecting thecathode rays, said pairs of plates being displaced from each otherangularly about the axis of the tube, of means for impressing voltagesfrom difierent sources upon pairs of said deflection plates in difierenttubes, a common sweep" circuit across which the other pairsbf deflectionplates are connected, and light-deflecting means for causing the linesof the luminous traces upon said screens to appear to the vision or theobserver to bev superposed, said deflecting means being non-diffusingwhereby each of said luminous lines as traced upon said screen shall bepreserved in its original definition to the vision of the observer.

3. The combination with a plurality of cathode ray tubes having screensadapted to become lumbnous under the influence of the cathode rays, eachof said tubes having pairs of deflection plates for deflecting thecathode rays, said pairs of plates being displaced from each otherangularly about the axis of the tube, of means for impressing voltagesfrom different sources upon pairs of said deflection plates in differenttubes, means for impressing sweep" voltages of the same frequency uponthe other pairs of deflection plates in said tubes respectively, andlight-deflecting means for deflecting the apparent location of a, lineon one of the screens to an apparent location where it appears to thevision of the observer to be su perposed on the line on another of saidscreens,

said deflectingv means being non-diffusing whereby each oi said luminouslines as traced upon said screen shall be preserved in its originaldeflnition to the vision of the observer.

4. The combination with a plurality of cathode ray tubes having screensadapted to become luminous under the influence of the cathode rays, eachof said tubes having pairs of deflection plates for deflecting thecathode rays, said pairs of plates being displaced from each otherangularly about the axis of the tube, of means for impressing voltagesfrom difierent sources upon pairs of said deflection plates in differenttubes, a common sweep circuit across which the other pairs of deflectionplates are connected, and light-deflecting means for deflecting theapparent location of a line on one of the screens to an apparentlocation where it appears to the vision of the observer to be superposedon the line of another of said screens, said deflecting means beingnon-diffusing whereby each of said luminous lines as traced upon saidscreen shall be preserved in its original definition to the vision ofthe observer.

5. The combination with a plurality of cathode ray'tubes having screensadapted to become luminous under the influence of the cathode rays, eachof said tubes having pairs of deflection plates for deflecting thecathode rays. said pairsof plates being displaced from each otherangularly about the axis of the tube, of means for impressing voltagesfrom different sources upon pairs of said deflection plates in differenttubes, means for impressing sweep" voltages of the same frequency uponthe other pairs of deflection plates in said tubes respectively, andlightdeflecting means for causing the lines of the luminous traces uponsaid screens to appear to the vision of the observer to be superposed,said deflecting means being non-diffusing whereby each of said luminouslines as traced upon said screen shall be preserved in its originaldefinition to the vision of the observer, and means for biasing thpotential of a pair of electrodes to shift the position of the line onthe screen of the tube.

6. The combination with a plurality of cathode ray tubes having screensadapted to become luminous under the influence of the cathode rays, eachof said tubes having pairs of deflection plates for deflecting thecathode rays, said pairs of plates being displaced from each otherangularly about the axis of the tube, of means for impressing voltagesfrom different sources upon pairs of said deflection plates in diiferenttubes, means for impressing sweep voltages of the same frequency uponthe other pairs of deflection plates in said tubes respectively, andlight-deflecting means for causing the lines of the luminous traces uponsaid screens to appear to the vision of the observer to be superposed,said deflecting means being nondiffusing whereby each of said luminouslines as traced upon said screen shall be preserved in its originaldefinition to the vision of the observer, the distances along the pathsof the light rays from the screens to the eye of the observer beingsubstantially equal. v

7. The combination with a plurality of cathode ray tubes having screensadapted to become luminous under the influence of the cathode rays, eachof said tubes having pairs of deflection plates for deflecting thecathode rays, said pairs of plates being displaced from each otherangularly about the axis of the tube, of means for impressing voltagesfrom difierent sources upon pairs of said deflection plates in differenttubes, means for impressing sweep voltages of the same frequency uponthe other pairs of deflection plates in said tubes respectively, andlight-deflecting means for causing the lines of the luminous traces uponsaid screens to appear to the vision of the observer to be superposed,said deflecting means being non-diffusing whereby each of said luminousoutlines as traced upon said screen shall be preserved in its originaldefinition to the vision of the observer, said deflecting meanscomprising a non-diffusing reflector receiving the light rays from oneof said screens and reflecting it to the reflecting surface of atransparent reilector which-reflects the last-mentioned rays to the eyeof the observer, another of said screens having its light raystransmitted through said transparent reflector to the eye of theobserver.

8. The method of comparing cathode ray outlines which consists insupplying voltages to be compared to deflector plates respectively ofdifierent cathode ray tubes, each of said tubes having a screen adaptedto be rendered luminous by cathode rays and having sweep electrodesaaaaaee angularly displaced from the aforesaid electrodes, applying"sweep" voltages of the same frequency to the said "sweep electrodes ofsaid tubes, and deflecting cathode-ray-produced light rays withoutdiffusion to the eye of the observer, so that the luminous outlinestraced upon the screens will appear to the vision of the observer intheir original definition and superposed.

9. The method of comparing cathode ray outlines which consists insupplying voltages to be compared to deflector plates respectively ofdifferent cathode ray tubes, each of said tubes having a screen adaptedto be rendered luminous by cathode rays and having sweep electrodesangularly displaced from the aforesaid electrodes, applying sweepvoltages of the same frequency to the said "sweep electrodes of saidtubes, and deflecting cathode-ray-produced light rays to the eye or theobserver, so that the luminous lines traced upon the screens will appearto the vision of the observer in their original definition andsuperposed.

FREDERICK W, FRINK.

